For example, an apparatus is known in which an irradiation apparatus having an optical fiber housing pipe housing an optical fiber guiding laser light from a pulse laser light source to emit from a laser light emission part and a mirror housing pipe provided at a tip portion of the optical fiber housing pipe housing a reflection mirror having an aspherical shaped reflection surface disposed with a predetermined distance from the laser light emission part inside thereof and provided with a laser irradiation window to irradiate reflected laser light to an irradiation point at a circumferential surface thereof; a liquid feed means feeding cleaning liquid to the irradiation point of the laser light; and a moving apparatus moving the irradiation apparatus in an axial direction are included.
According to this apparatus, the laser light emitted from the optical fiber is reflected by the aspherical reflection mirror to be condensed and irradiated to an application surface, and therefore, it is not necessary to house a condenser lens to condense the laser light in the irradiation apparatus, and an outside diameter of the irradiation apparatus can be made thin for the extent. Besides, the aspherical mirror housing pipe and the optical fiber housing pipe are disposed concentrically with respect to the irradiation apparatus, and the mirror housing pipe is spirally rotated by a rotation driving device, and thereby, it becomes possible to perform a laser process on an inner surface of a pipe.